Dishwashing machine



June 24, 1969" D. S.,CUSHING DISHWASHING MACHINE Filed Oct. 19, 1967 Sheet of 2 INVENTOR. DONALD s cusH 1M6 HiS ATTORNEY United States Patent 3,451,400 DISHWASHING MACHlNE Donald S. Cushing, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Oct. 19, 1967, Ser. No. 676,530 Int. Cl. 120% 3/02 US. Cl. 134-58 11 Claims ABSTRACT OF THE DISCLOSURE An automatic dishwasher comprising: a washing enclosure for receiving and containing articles to be washed therein, means for supplying liquid to the enclosure, spray means in the lower portion of said enclosure for effecting a washing action on the articles by ejecting pressurized liquid thereon, a pump connected between the enclosure and the spray means for circulating fluid from the enclosure to the spray means, and means for periodically limiting the volume of liquid supplied to the enclosure by the supply means to an amount such that the pump is only partially primed and the range of the liquid ejected by the spray means is substantially limited to the lower portion of the enclosure.

Background of the invention This invention relates generally to automatic dishwashers and more particularly to means for reducing redeposition of food solids on the articles washed in automatic dishwashers.

Many conventional dishwashers include a washing enclosure, vertically-spaced upper and lower racks for supporting articles to be washed, within the enclosure, means for supplying liquid to the enclosure including an electrically-operated inlet valve, spray means in the lower portion of the enclosure for effecting a washing action on the articles by ejecting pressurized liquid thereon and an electrically-operated motor-pump assembly alternatively operable to circulate liquid from the enclosure through the spray means or to discharge liquid from the enclosure to a drain.

The operational sequence of such conventional dish- Washers usually involves in order, one or more pro-rinse periods, a wash period, and one or more post-rinse periods. The last post-rinse period is normally followed by a drying period wherein the dishes are heated by an electrical heating element to facilitate their drying. Control means are provided to sequentially energize and deenergize the various electrically-operated components of the dishwasher to carry out the operational cycle. Generally, a sequence control means having a timer motor and several cam operated switches is provided, with each switch controlling one of the components. In such conventional machines, the electrically-operated inlet valve is usually of a type which, when open, passes liquid at a fixed volumetric rate. Hence, the amount of liquid admitted to the enclosure is proportional to the length of the time the inlet valve is opened by its cam-operated switch in the sequence control means. conventionally, the cam for that switch is so configured and arranged that each time it opens the inlet valve, it will maintain the same open long enough to admit enough liquid into the enclosure so that the motor-pump will be fully primed, whereby the range of liquid ejected from the spray means will extend throughout the full height of the enclosure during each of the conventional pre-rinse, wash and postrinse periods.

In such conventional dishwashers, the articles having the most gross food solids, such as pots, pans, plates and platters are generally located within the lower rack in the lower portion of the washing enclosure. It would be 3,451,400 Patented June 24, 1969 desirable to provide means for rinsing; only these lower portion articles and flushing the solids thus removed out of the enclosure to the drain before initiating the fullscale" first pre-rinse period which is conventionally used to rinse down all of the articles in both the upper and lower portions of the washing enclosure. Such an initial lower portion rinse and flush would greatly reduce the amount of solids which would otherwise be distributed throughout the entire extent of the washing enclosure during the subsequent conventional full-scale pre-rinse, wash and post-rinse periods and, hence, would greatly reduce the redeposition of solids on the articles. It would also be advantageous to provide another such lower portion rinse and flush drain immediately following the conventional full-scale first pre-rinse and prior to initiation of the remainder of the conventional. dishwasher operational cycle, in order to remove the food solids that are initially removed from the articles in the upper enclosure and dropped on the articles in the enclosure lower portion by the conventional full-scale pre-rinse.

Summary 07 the invenrion In accordance with the present invention, it has been found that such desirable lower portion rinsing as previously noted can be incorporated into conventional dishwashers of the type described above by providing means for periodically limiting the volume of liquid admitted by the liquid supply means to the enclosure to an amount such that the pump is only partially primed, whereby the pressure of the liquid pumped to the spray means is so reduced that the range of the liquid ejected from the spray means is substantially limited to the lower portion of the washing enclosure.

In one form of the present invention, the means for periodically limiting the volume of liquid admitted are provided by modifying the configuration and arrangement of the cams for the cam-operated switches of the sequence control means which control the electrically-operated inlet valve and electrically-operated motor-pump in such a manner that the pump will be only partially primed and such a lower portion rinse will occur at least before, and preferably before and after, the conventional fullscale first pre-rinse period and that each such lower portion rinse will be followed by a flush during which the food solids removed by the lower portion rinsing will be pumped to the drain.

Brief description of the drawings The present invention as illustrated in the accompanyin g drawings, wherein:

FIGURE 1 is a front elevational view, partly cut away to show details, of an automatic dishwasher employing the present invention;

FIGURE 2 is a schematic representation of the electrical circuitry of the control system of the present invention; and

FIGURES 3 and 4 are sequence control cam charts illustrating a presently preferred sequence of operation of the schematically shown switches in FIGURE 2, with FIGURE 3 showing the early portion of the operational sequence and FIGURE 4 the later portion.

Description of the preferred embodiments Referring now to the drawings and particularly to FIG- URE 1 thereof, there is illustrated an automatic dishwasher 10 having an outer cabinet 11 defining therein a washing enclosure 12. Disposed within the washing enclosure 12 are upper and lower racks 13 and 14 which are adapted to receive and support dishes or other articles to be washed within the washing enclosure 12. A door 15 is provided in one wall of the cabinet 11,, pivotal about a hinge means 16 to provide access to the washing enclosure 12. When the door 15 is pivoted downwardly, the upper rack 13 can be at least partially withdrawn from the upper portion of the washing enclosure 12 by means of a slide and roller system 17 provided at each side of the upper rack 13 and slidably supporting the upper rack 13 on the inner wall of the cabinet 11. Similarly the lower rack 14 can be at least partially withdrawn from the lower portion of the washing enclosure 12 by means of a roller 18 which rides upon a track 19 provided at each side of the cabinet 11.

Means including an electrically-operated inlet valve 20, are provided for supplying water, or other liquids, to the Washing enclosure 12. The valve 20 is supported on a bracket 21 fastened by welding, or other suitable fastening means, to the exterior of a side wall of the cabinet 11 at an elevation preferably between the racks 13 and 14. The inlet of the valve 20 is connected to a conduit 22 which communicates with a normal household plumbing system (not shown) and its outlet is connected to a conduit 23 which communicates with the washing enclosure 12 through an inlet funnel 24 formed as an embossment on the cabinet side wall at a point spaced below bracket 21. The conduit 23 is spaced from the funnel 24 so as to provide the conventional air-gap that is required by plumbing codes, and this spacing also permits the passage of air, or other gases, between the exterior of the cabinet 11 and the washing enclosure 12.

The lower extremity of the washing enclosure 12 is defined by a bottom wall 25 which gradually slopes to a low point 26 near the center of the dishwasher. Disposed below the low point 26 is a sump 27 which may be formed integrally with the bottom wall 25 or which may be a separate element secured thereto. Projecting upwardly from the bottom Wall 25 near the center of the wash chamber 12 is a pedestal 28 which rotatably supports a spray device 29. The spray device 29 has a plurality of orifices 30 through which liquid is ejected to effectuate a wash action upon articles supported by racks 13 and 14. At least one of the orifices 30 is directed such that the reaction force created by fluid passing therethrough causes rotation of the spray device 29.

Fluid is circulated into the spray device 29 by a pump 31 which is driven by a unidirectional electric motor 32. The pump 31 and motor 32 are secured together to form a motor-pump assembly 33 which is suitably supported from the bottom wall 25. A flexible boot or conduit 34 interconnects the sump 27 to the inlet 35 of the pump 31. The boot 34 is secured to the sump 27 by means of a clamp 36 and is similarly secured to the pump inlet 35 by means of another clamp 37.

Disposed within the housing of the pump 31 is an impeller (not shown) mounted for rotation to pump fluid through the pump housing and driven by the motor 32. A first or spray outlet 38 interconnects the pump 31 and the spray device 29, while a second or drain outlet 39 connects the pump 31 with a normal household sewer system (not shown) through a conduit (not shown). The first outlet 38 is connected to a flexible conduit 40 by means of a clamp 41. The conduit 40 extends to a fitting 42 on which the spray device 29 is rotatably mounted, it being understood that the fitting 42 is secured to the pedestal 28. With this arrangement, water, or any other fluid, entering the pump 31 through its inlet 35 will be pumped either into the spray device 29 through the first pump outlet 38 or discharged from the dishwasher through the second pump outlet 39 to the sewer system.

An outlet valve mechanism is provided to selectively control through which of the outlets 38 or 39 the fluid will egress from the pump 31. The outlet valve mechanism includes a frame 43 suitably secured to the exterior of the housing of the pump 31. The frame 43 carries a solenoid 44 having electrical terminals and an armature 45. The armature 45 is adapted to be drawn into the solenoid 44. The solenoid 44 is energized by the presence of the electrical energy across its terminals. The armature 45 is suitably linked to a valve element (not shown) 4 which is pivotally mounted within the housing of the pump 31. The valve element is biased by a spring 46, connected between it and the frame 43, toward a circulate position to seal oif the second or drain outlet 39 and thus direct fluid from the pump 31 through the first or spray outlet 38 to the spray device 29 when solenoid 44 is deenergized. When the solenoid 44 is energized, the armature 45 is drawn into the solenoid 44 and the valve element is pivoted through its linkage with the armature 45 towards a drain position to seal olf the first or spray outlet 38 and direct fluid from the pump 31 through the second or drain outlet 39 to the household sewer system. The foregoing outlet valve mechanism for the pump 31 is described in greater detail along with other refinements thereof in US. Patent No. 3,367,368 issued Feb. 6, 1968, to Thomas E. Jenkins, and assigned to the General Electric Company, assignee of the present invention. The present application does not claim as new the outlet valve mechanism per se. An electrical heating element 47 is supported in spaced relationship from the bottom Wall 25 and may be employed to heat fluid within the washing enclosure 12, although not so adapted in this application, and to facilitate the drying of the articles supported by racks 13 and 14 upon completion of the wash and post-rinse operations.

A sequence control means 48, having a manually operable knob 49, is conveniently positioned on the door 15. The sequence control means 48 is disposed within the door 15 and the knob 49 projects through the front wall thereof to be conveniently manipulated by the operator of the dishwasher 10.

Referring now to FIGURES 2-4, the control system for a presently preferred embodiment of the invention and its predetermined sequence of operation are schematically and graphically represented. The control system comprises the sequence control means 48 which includes a synchronous electric timer motor 50 that drives a plurality of earns 51, 52, 53, 54 and 55, which control, respectively, normally open switch elements 56, 57, 58, 59 and 60. The knob 49, timer motor 50 and cams 51-55 are, of course, mechanically interconnected in a wellknown manner.

Power is introduced in the control system through terminals L and L A master switch 61 is operative with the closing of the door 15 such that the control system cannot be energized until the door 15 is securely closed. The switch 56 controls the energization of the timer motor 50, which, when energized drives all of the cams 51-55. The switch element 57 controls the opening and closing of the liquid inlet valve 20 and, when closed, energizes the solenoid 20a to open the inlet valve 20. The switch element 58 controls the energization of a pump motor 32. The switch element 59 controls the position of the valve element within the pump 31 and, when closed, energizes the solenoid 44 to move the valve element from its circulate to its drain position. The switch element 60 controls energization of the heating means 47.

The liquid inlet valve 20 is of a well-known type and is operated by the solenoid 20a. When the solenoid 20a is energized by closure of cam-operated switch element 57, the liquid inlet valve 20 is fully opened. When the switch element 57 is open, the valve 20 is fully closed. The valve 20 is of a type that, when in its fully opened position, passes liquid at a fixed volumetric rate. Hence, the volumetric amount of liquid admitted to the washing enclosure 12 is proportional to the length of the time that the inlet valve 20 is opened through energization of the solenoid 20a by closure of the switch element 57 by the cam 52.

The conventional configuration and arrangement of the cams 51-55 is usually such that a conventional complete operational cycle of the dishwasher 10 involves, in order: one or more pre-rinse periods; a wash period; and one of more post-rinse periods. The last post-rinse period is normally followed by a drying period wherein the articles are heated by the electrical heating element 47 to facilitate their drying. Each of the conventional prerinse, wash and rinse operations include in order: (1) a fill period wherein the pump motor 32 is de-energized and the water inlet valve 20 is opened to admit liquid to the washing enclosure 12, (2) rinse or wash period wherein the liquid inlet valve 20 is closed and the pump motor 32 is energized with the pump valve positioned in its circulate position to direct liquid from the washing enclosure 12 to the spray device 29, and (3) a drain period wherein the liquid inlet valve 20 is. closed and the pump motor 32 remains energized with the pump valve element shifted into its drain position to direct liquid from the washing enclosure 12 to the household sewer system. The conventional configuration and arrangement of the cam 52 is such that the switch 57 will be closed for a suflicient length of time during each of the conventional fill periods to admit enough liquid to the washing enclosure 12 so that the pump 31 will be fully primed throughout each subsequental rinse or wash period, whereby the range of liquid ejected from spray device 30 will extend throughout the full height of the washing enclosure 12.

As previously noted, the articles having the most gross food solids, such as pots, pans, plates and platters are generally located in the lower rack 14 within the lower portion of the washing enclosure 12. It would be desirable to provide means for rinsing only these lower portion articles and then flushing the solids thus removed out of the washing enclosure 12 to the household sewage system before initiating the conventional fullscale first pre-rinse period which is used to rinse down all of the articles in both the upper and lower portions of the washing enclosure 12. It would also be advantageous to provide another such lower portion rinse and flush drain immediately following the conventional fullscale first pre-n'nse and prior to initiation of the remainder of the conventional dishwasher operational cycle.

J11 accordance with the present invention it has been found that such desirable lower portion rinsing can be incorporated into conventional dishwashers of the foregoing type by providing means for periodically limiting the volume of liquid admitted by the liquid inlet valve 20 to the washing enclosure 12 to an amount such that the pump 31 is only partially primed and a mixture of liquid and air is admitted to the pump inlet 35, whereby the pressure of the liquid pumped to the spray device 29 is so reduced that the range of the liquid ejected from the spray device orifices 30 is limited to the lower portion of the washing enclosure 12.

As best illustrated in FIGURES 2 and 3, this is accomplished in a presently preferred embodiment of the present invention by so modifying the configuration and arrangement of the cams 56-60 within the sequence control means 48 so that the early portion of the operational cycle for the dishwasher includes, in order:

(1) An initial lower portion rinse period in which the cam 53 closes the switch element 58 and energizes the pump motor 32, the cam 52 holds the switch element 57 closed just long enough to open the inlet valve to admit only enough liquid to the washing enclosure 12 so that the pump inlet 35 will be only partially primed with the mixture of liquid and air admitted through the inlet funnel 24, and the cam 54 allows the switch element 59 to remain open so that the pump valve element is held in its circulate position by the spring 46, whereby the discharge of the pump 31 is directed to the spray device '29 and the pressure of the liquid ejected by the orifices 30 is so reduced that the range of liquid so ejected is substantially limited to the lower portion of the washing enclosure 12;

(2) A drain period in which the cam 53 continues to hold the switch element 58 closed and the pump motor 32 remains energized, the cam 52 allows the switch element 57 to open and thus closes the liquid inlet valve 20, and the cam 54 closes the switch element 59 energizing the solenoid 44 to move the pump valve element to its drain position, whereby the liquid and food solids removed during the lower portion rinse period are pumped out of the washing enclosure 12 and into the sewer system;

(3) A fill period in which cam 53 allows the switch element 58 to open and de-energize the pump motor 32, the cam '54 allows the switch element 59 to open deenergizing the solenoid 44 and permitting the spriing 46 to return the pump valve element to its circulate position, and cam 52 closes the switch element 57 for a long enough time to open the inlet valve 20 to admit a sufficient amount of liquid to the washing enclosure 12 to fully prime the pump inlet 35 with liquid;

(4) A full-scale pre-rinse period in which the cam 52 allows the switch element 57 to open and thus close the inlet valve 20, the cam 54 continues to allow the switch element 59 to remain open and the pump valve element to remain in its circulate position, and the cam 53 closes the switch element 58 and energizes the pump motor 32 whereby liquid is circulated from the washing enclosure to the spray device 29 and the pressure of the liquid ejected from the orifices 30 is great enough that the range of the liquid so ejected extends throughout the full height of the washing enclosure 12 whereby food solids are removed from articles in both the upper and lower portions thereof;

(5) Another drain period in which cam 52 continues to allow the switch element 57 to remain open and the inlet valve 20 remains closed, the cam 54 closes the switch element 59 energizing the solenoid 44 to move the pump valve element to its drain position, and the cam 53 holds the switch element 58 closed to maintain energization of the pump motor 32 to pump the liquid and food solids into the sewer system;

(6) Another lower portion rinse period in which the cam 53 holds the switch element 58 closed to maintain energization of the pump motor 32, the cam 54 allows the switch element 59 to open so that the solenoid 44 is de-energized and the pump valve element is returned to its circulate position by the spring 46, and the cam 52 holds the switch element 57 closed just long enough to open the inlet valve 20 to admit only enough liquid to the washing enclosure 12 so that the pump inlet 35 will be only partially primed with a mixture of liquid and air admitted through the inlet funnel 24, whereby the discharge of the pump 31 is directed to the spray device 29 and the pressure of liquid is ejected from the orifices 30 is so reduced that the range of liquid so ejected is substantially limited to the lower portion of the washing enclosure 12;

(7) And still another drain period in which the cam 53 continues to hold the switch element '58 closed and the pump motor 32 remains energized, the cam 52 allows a switch element 57 to open and thus close the liquid inlet valve 20, and the cam 54 closes the switch element 59 energizing the solenoid 44 to move the pump valve element to its drain position, whereby the liquid and food solids removed during the other lower portion rinse period are pumped to the sewer system.

As illusthated in FIGURES 2 and 4, the later portion of the dishwasher operational cycle immediately follows the second lower portion flush period and preferably includes a pre-rinse period, a wash period and three post-rinse periods followed by a drying period. As illustrated in FIGURE 4, each of these later portions pre-rinse, wash and post-rinse periods include, in order:

(1) A fill period in which the cam 53 allows the switch element 58 to open and de-energize the pump motor 32, the cam 54 allows the switch element 59 to open deenergizing the solenoid 44 and allowing the spring 46 to move the pump valve element to its circulate position, and the cam 52 closes the switch element 57 for a long enough time to open the inlet valve 20 to admit a sufiicient amount of liquid to the washing enclosure to fully prime the pump inlet 35 with liquid;

(2) A rinse or wash period in which the cam 52 al- 'lows the switch element 57 to open and thus closes the inlet valve 20, the cam 54 continues to allow the switch element 59 to remain open and the pump valve element to remain in its circulate position, and the cam 53 closes the switch element 58 to energize the pump mo tor 32, whereby liquid is circulated from the washing enclosure 12 to the spray device 29 and the pressure of the liquid ejected from the orifices 30 is great enough that the range of liquid so ejected extends throughout the full height of the washing enclosure 12; and

(3) A drain period in which the cam 52 allows the switch element 57 to remain open and the inlet valve 20 to remain closed, the cam 54 closes the switch element 59 energizing the solenoid 44 to move the pump valve element to its drain position and the cam 53 holds the switch element '58 closed and the pump motor 32 energized to pump the liquid and any additional food solids removed from washing the articles to the sewer system.

The cams 52, 53 and 54 are so configured and arranged as to allow the switch elements 57, 58 and 59 to remain open following completion of the last post-rinse drain period, whereby the inlet valve 20 remains closed and the pump motor 32 remains de-energized for the remainder of the operational cycle. The cam 55 is so configured and arranged to allow the switch element 60' to remain open from the beginning of the operational cycle until the completion of the last post-rinse drain period at which time it closes the switch element 60 and maintains the same closed and the electric heating means 47 energized for the remainder of the operational cycle.

Of course, the configuration of the cam 51 is made such that when the control knob 49 is initially manually rotated a few degrees at the beginning of the operational cycle, the cam 51 closes the switch element 56 to energize the timer motor 50 and from that moment on re tains the switch element 56 closed throughout the complete dishwasher operational cycle whereby the timer motor 50 continues to drive all the cams 5155 until the cam 51 allows opening of the switch element 56 at the end of the operational cycle.

The durations of the various periods of the dishwasher operational cycle are of course dependent upon the size of the valve 20 and the characteristics of the pump 36. FIGURES 3 and 4 illustrate time periods which have produced satisfactory results in an embodiment of the present invention wherein the valve 20 comprises a valve which, when fully opened, passes approximately 2 gallons per minute of water at a pressure of 8 p.s.i. gauge and the pump 36 comprises a pump which, when fully primed with liquid, ejects the liquid from the spray head orifices 35 to a height of approximately eight feet. By limiting the open time of the valve 20 to 30 seconds during each of the lower portion rinse periods, as shown in FIGURE 3, and thus only partially priming the pump 36, the height of the liquid ejected from the spray device orifices 35 is reduced to about 1% feet.

Thus it can be seen that the present invention provides a dishwasher having means for automatically rinsing and flushing substantially only the lower portion of the washing enclosure in which the articles having the largest amount of food solids are usually placed during the early part of the operational cycle. With this arrangement, the amount of food solids which would otherwise be re-distributed throughout the entire enclosure during subsequent full-scale rinsing and washing periods during the later portion of the cycle is greatly reduced and, hence, the problem of redeposition of food solids on the articles is greatly mitigated.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of construction of the examples illustrated and it is contemplated that various modifications and applications will occur to those skilled in the art. For example, one might substitute a motor-pump assembly utilizing a reversible motor, such as that described in detail in US. Patent No. 3,259,764, issued July 5, 1966 to N. L. Kendt, and assigned to the General Electric Company, the assignee of the present invention, for the assembly 33 (FIGURE 1) which employs a unidirectional motor 32. Or, one might, instead, utilize separate pumps, one for circulating fluid from the washing enclosure 12 to the spray device 29, and another for discharging fluid from the enclosure 12 to the household sewer system. It is therefore intended that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An automatic dishwasher comprising:

(a) a washing enclosure for receiving and containing articles to be washed therein;

(b) liquid supply means for supplying liquid to said enclosure;

(c) spray means in the lower portion of said enclosure for eifecting a washing action on the articles by ejecting pressurized liquid thereon;

(d) a fluid circulating pump having an inlet connected to said enclosure and an outlet connected to said spray means; and

(e) control means for periodically limiting the volume of liquid supplied to said enclosure by said supply means to an amount such that said pump is only partially primed therewith and the range of the liquid pumped to and ejected from said spray means is substantially limited to the lower portion of said enclosure.

2. The invention of claim 1, wherein said control means includes:.

(a) an electrically-operated valve in said liquid supply means; and

(b) sequence control means including a timer motor and switch means controlling the opening and closing of said valve and operated in a predetermined operational sequence by means driven by said timer motor.

3. The invention of claim 2, wherein:

(a) said valve is of a type wherein the amount of liquid supplied by said supply means to said enclosure is proportional to the length of time that said valve is opened; and

(b) said means driven by said timer motor comprises cam means so configured and arranged relative to said switch means that said predetermined operational sequence includes at least one period in which said valve is opened just long enough so that the amount of liquid supplied to said enclosure by said supply means during said period is only enough to partially prime said pump therewith.

4. The invention of claim 3, wherein said cam means is so configured and arranged relative to said switch means that said predetermined operational sequence further includes at least one other period in which said valve is opened long enough so that the amount of liquid supplied to said enclosure by said supply means during said other period is lon genough to fully prime said pump therewith.

5. The invention of claim 2, further including:

(a) a second outlet from said pump connected to drain means;

(b) electrically operated outlet valve means for selectively opening and closing said pump outlets; and

(c) second switch means in said sequence control means controlling the operation of said outlet valve means and operated in a predetermined operational sequence by second means driven by said timer motor.

6. The invention of claim 5, wherein:

(a) said pump is electrically-operated; and

(b) said sequence control means further includes third switch means controlling the operation of said puimp and operated in a predetermined sequence of operation by third means driven by said timer motor.

7. An automatic dishwasher comprising:

(a) a washing enclosure for receiving and containing articles to be washed therein;

(b) liquid supply means including an electricallyoperated valve for supplying liquid to said enclosure;

(c) said valve being of the type wherein the amount of liquid supplied to the enclosure by said supply means is proportional to the length of the time said valve is opened;

(d) spray means in the lower portion of said enclosure for effecting a washing action on the articles by ejecting pressurized liquid thereon;

(e) electrically-operated pump means selectively operable in a first operating condition to circulate fluid from said washing enclosure through said spray means and in a second operating condition to discharge fluid from said enclosure to drain means;

(f) sequence control means for operating said valve and pump means through an operational cycle in a predetermined operational sequence including, in order:

(aa) a first period in which said valve is opened just long enough to permit said supply means to supply only enough liquid to said enclosure to only partially prime said pump means and in which said pump means is operated in said first operating condition and the range of liquid ejected from said spray means is substantially limited to the lower portion of said enclosure, and

(bb) a second period, following said first period in which said pump means is operated in said second operating condition to direct the discharge of said pump means to said drain means.

8. An automatic dishwasher comprising:

(a) a washing enclosure for receiving and containing articles to be washed therein;

(b) liquid supply means including an electrically-operated valve for supplying liquid to said enclosure; (c) said valve being of a type wherein the amount of liquid supplied to said enclosure by said supply means is proportional to the length of time said valve is opened;

(d) spray means in the lower portion of said enclosure for effecting a washing action on the articles by ejecting pressurized liquid thereon;

(e) an electrically-operated pump for circulating fluid having an inlet connected to said enclosure;

(f) said pump having a first outlet connected to said spray means and a second outlet connected to drain means;

(g) electrically-operated outlet valve means for selectively opening and closing said pump outlets; and

(h) sequence control means for operating said valve,

pump, outlet valve means through an operational cycle in a predetermined operational sequence;

(i) said sequence control means including a timer motor and switch means for controlling the opening and closing of said valve and the operation of said pump and said outlet valve means and operated in said predetermined operational sequence by cam means driven by said timer motor; and

(j) said cam means being so configured and arranged relative to said switch means that said predetermined operation sequence includes, in order:

(aa) a first period in which said valve is opened just long enough to permit said supply means to supply only enough liquid to said enclosure to only partially prime said pump, and in which said motor and outlet valve means are operated to direct the discharge of said pump to said spray means and the range of liquid ejected from said spray means is limited to substantially the lower portion of said enclosure, and

(bb) a second period, following said first period, in which said pump and outlet valve means are operated to direct the discharge of said pump to said drain means.

9. The invention of claim 8, wherein said cam means are so configured and arranged relative to said switch means that said predetermined operational sequence further includes:

(a) a third period, following said second period, in which said valve is opened long enough to permit said supply means to supply a sufficient amount of liquid to said enclosure to fully prime said pump therewith and in which said pump and outlet valve means are operated to direct the discharge of said pump to said spray means and the range of the liquid ejected by said spray means extends substantially throughout the entire extent of said enclosure.

10. The invention of claim 9, wherein said cam means are so configured and arranged relative to said switch means that said predetermined operational sequence further includes:

(a) a fourth period, following said third period, which is substantially identical to said first period; and

(b) a fifth period, following the said fourth period, which is substantially identical to second period.

11. The invention of claim 8, wherein said cam means are so configured and arranged relative to said switch means that said first period occurs at the beginning of said predetermined operational sequence.

References Cited UNITED STATES PATENTS 3,034,518 5/1962 Butsch et a1. 3,134,386 5/1964 Jenkins 134-102 3,384,098 5/1968 Swetnam 134-102 XR DANIEL BLUM, Primary Examiner.

US. Cl. X.R. 103-113 

